The disclosed subject matter relates to the drive assembly of outboard motors for watercraft, and methods of use and manufacture thereof. More particularly, the disclosed subject matter relates to methods and apparatus that transfer drive torque generated by the internal combustion to the propeller of an outboard motor.
Related art watercraft can include a drive assembly configured in one of at least three different layouts: inboard motor (also referred to as an inboard drive), outboard motor (also referred to as an outboard drive), and inboard/outboard motor (also referred to as an I/O, or as a stern drive). Each of these drive assembly layouts can include advantage(s) and disadvantage(s) as compared to the other layouts and can be selected based on performance, maintenance, cost and/or any other appropriate targets set for the watercraft.
An outboard motor can include an internal combustion engine and other components, such as but not limited to a pair of bevel gears, a drive shaft, a propeller shaft, and a forward-neutral-reverse assembly. The outboard motor can be assembled as a self-contained unit. The outboard motor can be removably mounted to the transom to be positioned completely outside the hull of the watercraft. As a result, an outboard motor can provide easy maintenance of the drive assembly and can enhance or maximize space for passengers and cargo for a given hull size, as compared to an inboard layout or an inboard/outboard layout. Further still, an outboard motor can omit the vapor ventilation system of the inboard motor and the inboard/outboard motor.
The outboard motor can be mounted to the transom to pivot relative to the transom in order to steer the watercraft. Thus, a separate steering system can be omitted, as compared to an inboard motor. Further, the outboard motor can permit the entire drive assembly to pivot relative to the transom about a substantially horizontal axis. As a result, the trim angle of the drive assembly can be adjusted to lift the bow out of the water to enhance acceleration or operation in rough water conditions, or to maintain the hull substantially parallel to the water surface during steady cruising conditions in relatively calm waters.
In an outboard motor, the internal combustion engine is spaced a predetermined distance from the propeller shaft to which the propeller is attached. In order to reduce or minimize the number of components used in the drive assembly, the internal combustion engine is mounted with its crankshaft oriented substantially perpendicular to the propeller shaft. For example, the engine can be oriented so that the crankshaft extends in a substantially vertical direction, and the propeller shaft extends in a substantially horizontal direction. The crankshaft can be connected to the propeller shaft using a driveshaft and a pair of bevel gears.